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20 years of the Toyota Prius: A look at this revolutionary vehicle

Wednesday, August 1, 2018 - 07:00
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Has it really been 20 years since the first Toyota Prius was released? Yes, it was launched in Japan in December 1997 as a 1998 model. The Prius was launched in the U.S.A. in the summer of 2000 as a 2001 model. The Prius is now in its fourth generation. Whether or not you like the Prius, almost every other hybrid vehicle on the market today contains parts that were obviously patterned after the first Toyota Hybrid System (THS) in the first Prius. This was the world’s first mass produced hybrid vehicle, and it shocked the entire automotive industry upon its launch.

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(Photo courtesy of Toyota) Figure 1 - The 1995 Toyota Prius concept car

The development of the first Prius is an incredible story that is detailed in a 387-page book called The Prius that Shook the World by Hideshi Itazaki, published in 1999. Unfortunately, that book is out of print. I was able to find a used one on Amazon several months ago. I was able to get permission from Mr. Itazaki to share some of the information from his book with you. I will also share additional information I have collected over the years.

Why did Toyota build the Prius? According to my research, a combination of four factors inspired the development of the Prius.

  1. EPA Laws: In 1990, amendments were made to the U.S. Environmental Protection Agency’s (EPA) Clean Air Act of 1970. The automotive industry was directly impacted by new rules to reduce acid rain, reduce urban air pollution, and reduce toxic air emissions.
  2. CARB Laws: Also, in 1990, the California Air Resources Board (CARB) adopted the Zero Emission Vehicle (ZEV) mandate. Both of these changes in laws affected the ability of an automobile manufacturer to sell cars in California without meeting the new regulations by 1998-2003.
  3. Inequality: Further inspiration to build the Prius came from inequality of enforcement of U.S. laws. Toyota had already experienced situations where U.S. fuel economy and emissions laws were enforced on Japanese auto makers, while granting extra time to the Big-3 from Detroit to find ways for their cars to meet the requirements. Toyota Motor Corporation took these new regulations seriously.
  4. Pride: Because of inequality and probably some personal pride. Toyota Engineers decided they wanted to show people in the U.S.A. that a car can be practical, attractive, clean, and fuel efficient. They wanted to beat the Big-3 from Detroit to market with such a car.

G21 Project: In September of 1993 Toyota formed the Globe 21st Century (G21) project to research what the car of the future would look like, how it would operate, and how polluting it would be. The following ideas for a concept car resulted from the project:  1. It would have a roomy cabin with a high seat position. 2. Use an aerodynamic body design. 3. Achieve 20 km/L (47 mpg) fuel economy (50% Better than the car of the day). 4. Use a horizontally mounted efficient engine with direct fuel Injection. 5. Use an efficient Continuously Variable Transmission (CVT). 6. It would be a vehicle with no increased infrastructure requirements (unlike electric and Compressed Natural Gas (CNG) vehicles).

To make a long story short, the G21 project went through several phases as progress towards the development of a concept car from scratch proceeded. In late 1994, Toyota management decided that a 50% increase in fuel economy was not enough for a car of the 21st century, they directed the G21 group to double the fuel economy instead. 

A concept car (Figure 1) was built for the October 1995 Tokyo Motor Show. The car was built with an electric induction motor/generator sandwiched between a direct injected 1.5L gasoline engine and a push-belt CVT transmission. A capacitor was used to store, and release, energy as required. This system was described as the Toyota-EMS (Energy Management System – Figure 2) rather than a hybrid. Toyota wanted it kept secret that they were developing a hybrid vehicle.

(Photo courtesy of Toyota) Figure 2 - The 1995 Prius concept car Toyota-EMS (Energy Management System)

Toyota Hybrid System: As a result of the directive to double fuel economy, the G21 project group had to change everything; a new powertrain design had to be developed.  In June of 1995, at the final meeting of the G21, development of a hybrid vehicle was officially approved at the meeting and a code name " 890T" was assigned to the Prius. Toyota was determined to keep the development of their hybrid vehicle a secret. The hybrid system was named "Toyota Hybrid System (THS). Development of the new THS system presented many challenges. Most of the following challenges had never been accomplished in the automotive industry. Toyota had to pioneer the design of each of these from scratch.

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